Low endoscopy completion rates are a major problem in the VA, causing delay or failure to receive essential care, increased clinic wait times, lost capacity, increased costs, thus limiting endoscopic screening for colorectal cancer. This study tests whether an Interactive Voice Response (IVR) messaging system is equally effective in promoting the completion of flexible sigmoidoscopy and colonoscopy as usual clinical care practices that include phone calls from nurses to patients prior to preparation and procedures. Previous studies have examined the role of scheduling facilitation or patient adherence on endoscopy completion and the use of IVR technology to enhance patient adherence in other medical contexts. This is the first study, however, to evaluate the use of IVR for endoscopy completion and the first to compare it to the effectiveness of phone calls from nurses prior to an endoscopy appointment.